The present invention comprises a chemical sensor for selectively detecting an analyte in a solution, a method of selectively detecting an analyte in a solution, and use of the chemical sensor.
A chemical sensor is a device which selectively detects a target molecule (analyte) in a complex medium (the sample solution) and provides an output signal which is proportional to the concentration of the studied analyte. A chemical sensor consists of two neighbouring components, the so-called recognition element and the transducer component. The function of the recognition element is to selectively bind to the analyte located in the sample solution. In binding, this or subsequent chemical events should be converted into a quantifiable electric output signal of the transducer component. A large number of combinations of different recognition elements and transducer components have previously been reported1, 2, 3. The classification of the recognition element can be effected on the basis of a biologic or non-biologic origin, and if it has catalytic or non-catalytic properties (see Table 1). The transducer component is based on different operating principles which can be of electrochemical, optical, magnetic, acoustic/piezoelectric or thermometric nature.
The capacity of a chemical sensor can be described by parameters, such as selectivity, sensibility, stability, response time and re-usability. A large number of different sensor concepts have been presented, of which the so-called biosensors have shown very promising properties in respect of selectivity and sensibility to a large number of analytes. Unfortunately, the stability is not good owing to their function being based on recognition elements of biological origin.
Enfors, Sxe2x80x94O and Nilsson, H, 1979 (4) described a biosensor with a manually exchangeable recognition element. This biosensor is operated by injecting a solution of an enzyme into the biosensor. The response is measured as a pH signal. A large excess of enzyme solution must be used. In order to get a relevant value of the pH response, the authors state that the solution must be kept still in the biosensor. Slow regeneration is expected because the analyte and the formed enzymatic products have to diffuse out from the biosensor prior to new measurments can be initiated. Furthermore, there must be introduced a second transducer component in the system, that is a pH electrode measuring the pH of the surrounding sample solution.
GBF, Scientific Annual Report 1990, pp 62-63 and 126-127, Biosensors for Pesticides in Water, describes a biosensor based on a liquid flow, into which different substrates are injected. The flow is passing a selective membrane reactor, in which antibodies are immobilised. Thus, this biosensor is based on a flowing analyte detected by a stationary recognition element.
Various approaches in Flow Injection Analysis (FIA) require sample pretreatment, have possible contamination of the flow-through system/detector, operation in harsh chemical environments not possible, no on-line or in situ monitoring is possible, samples must be taken (Ruzicka, J. and Hansen, E. T. xe2x80x98Flow Injection Analysisxe2x80x99, John Wiley and Sons, NY, 1981).
In one aspect of the present invention, there is provided a new type of chemical sensor.
In another aspect of the present invention, there is provided a method of selectively detecting an analyte in a solution.
In yet another aspect of the present invention, there is provided the use of the sensor according to the invention for different applications.